Princess of Numbers also known as the Princess of Math Puppy first appeared in the crossover special episode of Blue's Clues and Blue's Room Meet Blue's Baby Brother.
In Puppyville Blue along with Joe an Sprinkle were in the middle of playing the Special Edition of Blue's Clues called Gold Clues to figure out who is Blue's baby brother. As they arrive at Numbers Kingdom they saw a Royal purple puppy counting roses. Blue asked the royal puppy if she's Blue baby brother the Princess said no indicating she's a girl and introduced herself to them Joe decides to dress the part, returning in full armor as Knight Joe and speaking in medieval lingo. Princess Numbers puppy was charmed and impressed with Joe's Armor and his medieval speaking. She offers to help and show them through her castle because the second gold pawprint was inside on the top floor, but says that they must know all of the Clapping Codes to get through the doors. After getting to the top Sprinkles earns his Purple spots as a reward for learning his numbers.